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Bianco V, Korbelius M, Vujic N, Akhmetshina A, Amor M, Kolb D, Pirchheim A, Bradic I, Kuentzel KB, Buerger M, Schauer S, Phan HTT, Bulfon D, Hoefler G, Zimmermann R, Kratky D. Impact of (intestinal) LAL deficiency on lipid metabolism and macrophage infiltration. Mol Metab 2023; 73:101737. [PMID: 37182562 PMCID: PMC10209539 DOI: 10.1016/j.molmet.2023.101737] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Revised: 03/01/2023] [Accepted: 05/08/2023] [Indexed: 05/16/2023] Open
Abstract
OBJECTIVE To date, the only enzyme known to be responsible for the hydrolysis of cholesteryl esters and triacylglycerols in the lysosome at acidic pH is lysosomal acid lipase (LAL). Lipid malabsorption in the small intestine (SI), accompanied by macrophage infiltration, is one of the most common pathological features of LAL deficiency. However, the exact role of LAL in intestinal lipid metabolism is still unknown. METHODS We collected three parts of the SI (duodenum, jejunum, ileum) from mice with a global (LAL KO) or intestine-specific deletion of LAL (iLAL KO) and corresponding controls. RESULTS We observed infiltration of lipid-associated macrophages into the lamina propria, where neutral lipids accumulate massively in the SI of LAL KO mice. In addition, LAL KO mice absorb less dietary lipids but have accelerated basolateral lipid uptake, secrete fewer chylomicrons, and have increased fecal lipid loss. Inflammatory markers and genes involved in lipid metabolism were overexpressed in the duodenum of old but not in younger LAL KO mice. Despite the significant reduction of LAL activity in enterocytes of enterocyte-specific (iLAL) KO mice, villous morphology, intestinal lipid concentrations, expression of lipid transporters and inflammatory genes, as well as lipoprotein secretion were comparable to control mice. CONCLUSIONS We conclude that loss of LAL only in enterocytes is insufficient to cause lipid deposition in the SI, suggesting that infiltrating macrophages are the key players in this process.
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Affiliation(s)
- Valentina Bianco
- Gottfried Schatz Research Center, Molecular Biology and Biochemistry, Medical University of Graz, Graz, Austria
| | - Melanie Korbelius
- Gottfried Schatz Research Center, Molecular Biology and Biochemistry, Medical University of Graz, Graz, Austria
| | - Nemanja Vujic
- Gottfried Schatz Research Center, Molecular Biology and Biochemistry, Medical University of Graz, Graz, Austria
| | - Alena Akhmetshina
- Gottfried Schatz Research Center, Molecular Biology and Biochemistry, Medical University of Graz, Graz, Austria
| | - Melina Amor
- Gottfried Schatz Research Center, Molecular Biology and Biochemistry, Medical University of Graz, Graz, Austria
| | - Dagmar Kolb
- Core Facility Ultrastructure Analysis, Center for Medical Research, Medical University of Graz, Graz, Austria; BioTechMed-Graz, Graz, Austria
| | - Anita Pirchheim
- Gottfried Schatz Research Center, Molecular Biology and Biochemistry, Medical University of Graz, Graz, Austria
| | - Ivan Bradic
- Gottfried Schatz Research Center, Molecular Biology and Biochemistry, Medical University of Graz, Graz, Austria
| | - Katharina B Kuentzel
- Gottfried Schatz Research Center, Molecular Biology and Biochemistry, Medical University of Graz, Graz, Austria
| | - Martin Buerger
- Gottfried Schatz Research Center, Molecular Biology and Biochemistry, Medical University of Graz, Graz, Austria
| | - Silvia Schauer
- Diagnostics and Research Institute of Pathology, Medical University of Graz, Graz, Austria
| | - Huyen T T Phan
- Diagnostics and Research Institute of Pathology, Medical University of Graz, Graz, Austria
| | - Dominik Bulfon
- Institute of Molecular Biosciences, University of Graz, Graz, Austria
| | - Gerald Hoefler
- Diagnostics and Research Institute of Pathology, Medical University of Graz, Graz, Austria
| | - Robert Zimmermann
- BioTechMed-Graz, Graz, Austria; Institute of Molecular Biosciences, University of Graz, Graz, Austria
| | - Dagmar Kratky
- Gottfried Schatz Research Center, Molecular Biology and Biochemistry, Medical University of Graz, Graz, Austria; BioTechMed-Graz, Graz, Austria.
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2
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Pu J. Targeting the lysosome: Mechanisms and treatments for nonalcoholic fatty liver disease. J Cell Biochem 2022; 123:1624-1633. [PMID: 35605052 PMCID: PMC9617749 DOI: 10.1002/jcb.30274] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2022] [Revised: 04/24/2022] [Accepted: 05/02/2022] [Indexed: 11/11/2022]
Abstract
The multiple functions of the lysosome, including degradation, nutrient sensing, signaling, and gene regulation, enable the lysosome to regulate lipid metabolism at different levels. In this review, I summarize the recent studies on lysosomal regulation of lipid metabolism and the alterations of the lysosome functions in the livers affected by nonalcoholic fatty liver disease (NAFLD). NAFLD is a highly prevalent lipid metabolic disorder. The progression of NAFLD leads to nonalcoholic steatohepatitis (NASH) and other severe liver diseases, and thus the prevention and treatments of NAFLD progression are critically needed. Targeting the lysosome is a promising strategy. I also discuss the current manipulations of the lysosome functions in the preclinical studies of NAFLD and propose my perspectives on potential future directions.
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Affiliation(s)
- Jing Pu
- Department of Molecular Genetics and Microbiology, Autophagy, Inflammation, and Metabolism (AIM) Center of Biomedical Research Excellence, University of New Mexico, Albuquerque, New Mexico, USA
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3
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Ghanem M, Lewis GF, Xiao C. Recent advances in cytoplasmic lipid droplet metabolism in intestinal enterocyte. Biochim Biophys Acta Mol Cell Biol Lipids 2022; 1867:159197. [PMID: 35820577 DOI: 10.1016/j.bbalip.2022.159197] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2021] [Revised: 06/03/2022] [Accepted: 06/14/2022] [Indexed: 11/30/2022]
Abstract
Processing of dietary fats in the intestine is a highly regulated process that influences whole-body energy homeostasis and multiple physiological functions. Dysregulated lipid handling in the intestine leads to dyslipidemia and atherosclerotic cardiovascular disease. In intestinal enterocytes, lipids are incorporated into lipoproteins and cytoplasmic lipid droplets (CLDs). Lipoprotein synthesis and CLD metabolism are inter-connected pathways with multiple points of regulation. This review aims to highlight recent advances in the regulatory mechanisms of lipid processing in the enterocyte, with particular focus on CLDs. In-depth understanding of the regulation of lipid metabolism in the enterocyte may help identify therapeutic targets for the treatment and prevention of metabolic disorders.
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Affiliation(s)
- Murooj Ghanem
- Department of Anatomy, Physiology and Pharmacology, College of Medicine, University of Saskatchewan, Saskatoon, SK, Canada
| | - Gary F Lewis
- Departments of Medicine and Physiology, University of Toronto, and University Health Network, Toronto, ON, Canada
| | - Changting Xiao
- Department of Anatomy, Physiology and Pharmacology, College of Medicine, University of Saskatchewan, Saskatoon, SK, Canada.
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4
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Aqul AA, Ramirez CM, Lopez AM, Burns DK, Repa JJ, Turley SD. Molecular markers of brain cholesterol homeostasis are unchanged despite a smaller brain mass in a mouse model of cholesteryl ester storage disease. Lipids 2022; 57:3-16. [PMID: 34618372 PMCID: PMC8766890 DOI: 10.1002/lipd.12325] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Revised: 09/17/2021] [Accepted: 09/20/2021] [Indexed: 01/03/2023]
Abstract
Lysosomal acid lipase (LAL), encoded by the gene LIPA, facilitates the intracellular processing of lipids by hydrolyzing cholesteryl esters and triacylglycerols present in newly internalized lipoproteins. Loss-of-function mutations in LIPA result in cholesteryl ester storage disease (CESD) or Wolman disease when mutations cause complete loss of LAL activity. Although the phenotype of a mouse CESD model has been extensively characterized, there has not been a focus on the brain at different stages of disease progression. In the current studies, whole-brain mass and the concentrations of cholesterol in both the esterified (EC) and unesterified (UC) fractions were measured in Lal-/- and matching Lal+/+ mice (FVB-N strain) at ages ranging from 14 up to 280 days after birth. Compared to Lal+/+ controls at 50, 68-76, 140-142, and 230-280 days of age, Lal-/- mice had brain weights that averaged approximately 6%, 7%, 18%, and 20% less, respectively. Brain EC levels were higher in the Lal-/- mice at every age, being elevated 27-fold at 230-280 days. Brain UC concentrations did not show a genotypic difference at any age. The elevated brain EC levels in the Lal-/- mice did not reflect EC in residual blood. An mRNA expression analysis for an array of genes involved in the synthesis, catabolism, storage, and transport of cholesterol in the brains of 141-day old mice did not detect any genotypic differences although the relative mRNA levels for several markers of inflammation were moderately elevated in the Lal-/- mice. The possible sites of EC accretion in the central nervous system are discussed.
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Affiliation(s)
- Amal A. Aqul
- Department of Pediatrics, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas TX 75390 USA
| | - Charina M. Ramirez
- Department of Pediatrics, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas TX 75390 USA
| | - Adam M. Lopez
- Department of Internal Medicine, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas TX 75390 USA
| | - Dennis K. Burns
- Department of Pathology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas TX 75390 USA
| | - Joyce J. Repa
- Department of Internal Medicine, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas TX 75390 USA
- Department of Physiology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas TX 75390 USA
| | - Stephen D. Turley
- Department of Internal Medicine, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas TX 75390 USA
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5
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Lopresti MW, Cui W, Abernathy B, Fredrickson G, Barrow F, Desai AS, Revelo XS, Mashek D. Hepatic Lysosomal Acid Lipase Overexpression Worsens Hepatic Inflammation in Mice Fed a Western Diet. J Lipid Res 2021; 62:100133. [PMID: 34624333 PMCID: PMC8556525 DOI: 10.1016/j.jlr.2021.100133] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2021] [Revised: 09/16/2021] [Accepted: 09/23/2021] [Indexed: 02/07/2023] Open
Abstract
Nonalcoholic fatty liver disease (NAFLD) is characterized by the accumulation of lipid droplets in hepatocytes. NAFLD development and progression is associated with an increase in hepatic cholesterol levels and decreased autophagy and lipophagy flux. Previous studies have shown that the expression of lysosomal acid lipase (LAL), encoded by the gene LIPA, which can hydrolyze both triglyceride and cholesteryl esters, is inversely correlated with the severity of NAFLD. In addition, ablation of LAL activity results in profound NAFLD. Based on this, we predicted that overexpressing LIPA in the livers of mice fed a Western diet would prevent the development of NAFLD. As expected, mice fed the Western diet exhibited numerous markers of NAFLD, including hepatomegaly, lipid accumulation, and inflammation. Unexpectedly, LAL overexpression did not attenuate steatosis and had only minor effects on neutral lipid composition. However, LAL overexpression exacerbated inflammatory gene expression and infiltration of immune cells in mice fed the Western diet. LAL overexpression also resulted in abnormal phagosome accumulation and lysosomal lipid accumulation depending upon the dietary treatment. Overall, we found that hepatic overexpression of LAL drove immune cell infiltration and inflammation and did not attenuate the development of NAFLD, suggesting that targeting LAL expression may not be a viable route to treat NAFLD in humans.
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Affiliation(s)
- Michael W Lopresti
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis MN
| | - Wenqi Cui
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis MN
| | - Breann Abernathy
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis MN
| | - Gavin Fredrickson
- Department of Integrative Biology and Physiology, University of Minnesota, Minneapolis MN
| | - Fanta Barrow
- Department of Integrative Biology and Physiology, University of Minnesota, Minneapolis MN
| | - Arnav S Desai
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis MN
| | - Xavier S Revelo
- Department of Integrative Biology and Physiology, University of Minnesota, Minneapolis MN
| | - Douglas Mashek
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis MN; Department of Medicine, Division of Diabetes, Endocrinology and Metabolism, University of Minnesota, Minneapolis MN.
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6
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Kuentzel KB, Bradić I, Akhmetshina A, Korbelius M, Rainer S, Kolb D, Gauster M, Vujić N, Kratky D. Defective Lysosomal Lipolysis Causes Prenatal Lipid Accumulation and Exacerbates Immediately after Birth. Int J Mol Sci 2021; 22:10416. [PMID: 34638755 PMCID: PMC8508985 DOI: 10.3390/ijms221910416] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Revised: 09/24/2021] [Accepted: 09/24/2021] [Indexed: 12/03/2022] Open
Abstract
Cholesterol and fatty acids are essential lipids that are critical for membrane biosynthesis and fetal organ development. Cholesteryl esters (CE) are degraded by hormone-sensitive lipase (HSL) in the cytosol and by lysosomal acid lipase (LAL) in the lysosome. Impaired LAL or HSL activity causes rare pathologies in humans, with HSL deficiency presenting less severe clinical manifestations. The infantile form of LAL deficiency, a lysosomal lipid storage disorder, leads to premature death. However, the importance of defective lysosomal CE degradation and its consequences during early life are incompletely understood. We therefore investigated how defective CE catabolism affects fetus and infant maturation using Lal and Hsl knockout (-/-) mouse models. This study demonstrates that defective lysosomal but not neutral lipolysis alters placental and fetal cholesterol homeostasis and exhibits an initial disease pathology already in utero as Lal-/- fetuses accumulate hepatic lysosomal lipids. Immediately after birth, LAL deficiency exacerbates with massive hepatic lysosomal lipid accumulation, which continues to worsen into young adulthood. Our data highlight the crucial role of LAL during early development, with the first weeks after birth being critical for aggravating LAL deficiency.
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Affiliation(s)
- Katharina B. Kuentzel
- Gottfried Schatz Research Center, Molecular Biology and Biochemistry, Medical University of Graz, 8010 Graz, Austria; (K.B.K.); (I.B.); (A.A.); (M.K.); (S.R.); (N.V.)
| | - Ivan Bradić
- Gottfried Schatz Research Center, Molecular Biology and Biochemistry, Medical University of Graz, 8010 Graz, Austria; (K.B.K.); (I.B.); (A.A.); (M.K.); (S.R.); (N.V.)
| | - Alena Akhmetshina
- Gottfried Schatz Research Center, Molecular Biology and Biochemistry, Medical University of Graz, 8010 Graz, Austria; (K.B.K.); (I.B.); (A.A.); (M.K.); (S.R.); (N.V.)
| | - Melanie Korbelius
- Gottfried Schatz Research Center, Molecular Biology and Biochemistry, Medical University of Graz, 8010 Graz, Austria; (K.B.K.); (I.B.); (A.A.); (M.K.); (S.R.); (N.V.)
| | - Silvia Rainer
- Gottfried Schatz Research Center, Molecular Biology and Biochemistry, Medical University of Graz, 8010 Graz, Austria; (K.B.K.); (I.B.); (A.A.); (M.K.); (S.R.); (N.V.)
| | - Dagmar Kolb
- Gottfried Schatz Research Center, Cell Biology, Histology and Embryology, Medical University of Graz, 8010 Graz, Austria; (D.K.); (M.G.)
- Core Facility Ultrastructural Analysis, Medical University of Graz, 8010 Graz, Austria
- BioTechMed-Graz, 8010 Graz, Austria
| | - Martin Gauster
- Gottfried Schatz Research Center, Cell Biology, Histology and Embryology, Medical University of Graz, 8010 Graz, Austria; (D.K.); (M.G.)
| | - Nemanja Vujić
- Gottfried Schatz Research Center, Molecular Biology and Biochemistry, Medical University of Graz, 8010 Graz, Austria; (K.B.K.); (I.B.); (A.A.); (M.K.); (S.R.); (N.V.)
| | - Dagmar Kratky
- Gottfried Schatz Research Center, Molecular Biology and Biochemistry, Medical University of Graz, 8010 Graz, Austria; (K.B.K.); (I.B.); (A.A.); (M.K.); (S.R.); (N.V.)
- BioTechMed-Graz, 8010 Graz, Austria
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7
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Han SL, Qian YC, Limbu SM, Wang J, Chen LQ, Zhang ML, Du ZY. Lipolysis and lipophagy play individual and interactive roles in regulating triacylglycerol and cholesterol homeostasis and mitochondrial form in zebrafish. Biochim Biophys Acta Mol Cell Biol Lipids 2021; 1866:158988. [PMID: 34111526 DOI: 10.1016/j.bbalip.2021.158988] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Revised: 05/29/2021] [Accepted: 06/03/2021] [Indexed: 12/26/2022]
Abstract
Neutral lipases-mediated lipolysis and acid lipases-moderated lipophagy are two main processes for degradation of lipid droplets (LDs). However, the individual and interactive roles of these metabolic pathways are not well known across vertebrates. This study explored the roles of lipolysis and lipophagy from the aspect of neutral and acid lipases in zebrafish. We established zebrafish strains deficient in either adipose triglyceride lipase (atgl-/-; AKO fish) or lysosomal acid lipase (lal-/-; LKO fish) respectively, and then inhibited lipolysis in the LKO fish and lipophagy in the AKO fish by feeding diets supplemented with the corresponding inhibitors Atglistatin and 3-Methyladenine, respectively. Both the AKO and LKO fish showed reduced growth, swimming activity, and oxygen consumption. The AKO fish did not show phenotypes in adipose tissue, but mainly accumulated triacylglycerol (TAG) in liver, also, they had large LDs in the hepatocytes, and did not stimulate lipophagy as a compensation response but maintained basal lipophagy. The LKO fish reduced total lipid accumulation in the body but had high cholesterol content in liver; also, they accumulated small LDs in the hepatocytes, and showed increased lipolysis, especially Atgl expression, as a compensatory mechanism. Simultaneous inhibition of lipolysis and lipophagy in zebrafish resulted in severe liver damage, with the potential to trigger mitophagy. Overall, our study illustrates that lipolysis and lipophagy perform individual and interactive roles in maintaining homeostasis of TAG and cholesterol metabolism. Furthermore, the interactive roles of lipolysis and lipophagy may be essential in regulating the functions and form of mitochondria.
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Affiliation(s)
- Si-Lan Han
- LANEH, School of Life Sciences, East China Normal University, Shanghai, China
| | - Yu-Cheng Qian
- LANEH, School of Life Sciences, East China Normal University, Shanghai, China
| | | | - Jing Wang
- LANEH, School of Life Sciences, East China Normal University, Shanghai, China
| | - Li-Qiao Chen
- LANEH, School of Life Sciences, East China Normal University, Shanghai, China
| | - Mei-Ling Zhang
- LANEH, School of Life Sciences, East China Normal University, Shanghai, China
| | - Zhen-Yu Du
- LANEH, School of Life Sciences, East China Normal University, Shanghai, China.
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8
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Pritchard AB, Strong A, Ficicioglu C. Persistent dyslipidemia in treatment of lysosomal acid lipase deficiency. Orphanet J Rare Dis 2020; 15:58. [PMID: 32093730 PMCID: PMC7041253 DOI: 10.1186/s13023-020-1328-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Accepted: 02/07/2020] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Lysosomal acid lipase deficiency (LALD) is an autosomal recessive inborn error of lipid metabolism characterized by impaired lysosomal hydrolysis and consequent accumulation of cholesteryl esters and triglycerides. The phenotypic spectrum is diverse, ranging from severe, neonatal onset failure to thrive, hepatomegaly, hepatic fibrosis, malabsorption and adrenal insufficiency to childhood-onset hyperlipidemia, hepatomegaly, and hepatic fibrosis. Sebelipase alfa enzyme replacement has been approved by the Food and Drug Administration for use in LALD after demonstrating dramatic improvement in transaminitis and dyslipidemia with initiation of enzyme replacement therapy. METHODS A chart review was performed on 2 patients with childhood-onset, symptomatic LALD with persistent dyslipidemia despite appropriate enzyme replacement therapy to identify biological pathways and risk factors for incomplete response to therapy. RESULTS Two patients with attenuated, symptomatic LALD had resolution of transaminitis on enzyme replacement therapy without concomitant effect on dyslipidemia despite dose escalation and no evidence of antibody response to enzyme. CONCLUSION Enzyme replacement therapy does not universally resolve all complications of LALD. Persistent dyslipidemia remains a clinically significant issue, likely related to the complex metabolic pathways implicated in LALD pathogenesis. We discuss the possible mechanistic basis for this unexpected finding and the implications for curative LALD therapy.
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Affiliation(s)
- Amanda Barone Pritchard
- Present address: C.S. Mott Children's Hospital, Michigan Medicine, 1500 E Medical Center Dr, Ann Arbor, MI, 48109, USA
| | - Alanna Strong
- Division of Human Genetics and Metabolism, Children's Hospital of Philadelphia, 3401 Civic Center Blvd, Philadelphia, PA, 19104, USA
| | - Can Ficicioglu
- Division of Human Genetics and Metabolism, Children's Hospital of Philadelphia, 3401 Civic Center Blvd, Philadelphia, PA, 19104, USA.
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9
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Kohli R, Ratziu V, Fiel MI, Waldmann E, Wilson DP, Balwani M. Initial assessment and ongoing monitoring of lysosomal acid lipase deficiency in children and adults: Consensus recommendations from an international collaborative working group. Mol Genet Metab 2020; 129:59-66. [PMID: 31767214 DOI: 10.1016/j.ymgme.2019.11.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Revised: 11/15/2019] [Accepted: 11/16/2019] [Indexed: 02/06/2023]
Abstract
BACKGROUND Lysosomal acid lipase (LAL) deficiency is an ultra-rare, progressive, autosomal recessive disorder. Functional mutations in LIPA, the gene that encodes LAL, result in accumulation of cholesteryl esters and triglycerides in hepatocytes and in the macrophages of the intestines, vascular endothelial system, and numerous other organs. LAL deficiency has a broad clinical spectrum; children and adults can present with dyslipidemia, liver enzyme elevations, hepatosplenomegaly, hepatic steatosis, liver fibrosis and/or cirrhosis, and vascular disease, which may lead to significant morbidity and premature mortality in some patients. Given the systemic involvement and the wide range of healthcare specialists who manage patients with LAL deficiency, there is a need for guidelines to assess and monitor disease involvement. OBJECTIVES To provide a set of recommendations for the initial assessment and ongoing monitoring of patients with LAL deficiency to help physicians in various disciplines effectively manage the disease based on the observed presentation and progression in each case. METHODS A group of internationally recognized healthcare specialists with expertise in clinical genetics, pathology, hepatology, gastroenterology, cardiology, and lipidology convened to develop an evidence-based consensus of best practices for the initial assessment and ongoing monitoring of children and adults with LAL deficiency, regardless of treatment status; infants with LAL deficiency have been excluded from these guidelines because they require specialized care. RESULTS The authors present guidance for the assessment and monitoring of patients with LAL deficiency based on age and disease manifestations that include the hepatic, cardiovascular, and gastrointestinal systems. A schedule for ongoing monitoring of disease progression is provided. In addition, the need to establish an interdisciplinary and integrated care team to optimize the approach to managing this systemic disease is highlighted. CONCLUSIONS There is currently no published guidance on the assessment and monitoring of patients with LAL deficiency. These consensus recommendations for the initial assessment and ongoing monitoring of children and adults with LAL deficiency are intended to help improve the management of these patients.
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Affiliation(s)
- Rohit Kohli
- Division of Gastroenterology, Hepatology and Nutrition, Children's Hospital Los Angeles, Los Angeles, California, USA
| | - Vlad Ratziu
- Department of HepaGastroenterology, Université Pierre et Marie Curie, Hôpital Pitié Salpêtrière, Paris, France
| | - Maria Isabel Fiel
- Department of Pathology, Icahn School of Medicine at Mount Sinai Hospital, NY, New York, USA
| | - Elisa Waldmann
- Medizinische Klinik und Poliklinik IV, Klinikum der Ludwig-Maximilians-Universität München, Munich, Germany
| | - Don P Wilson
- Division of Pediatric Endocrinology & Diabetes, Cook Children's Medical Center, Fort Worth, TX, USA
| | - Manisha Balwani
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai Hospital, NY, New York, USA.
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10
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Lopez AM, Ramirez CM, Taylor AM, Jones RD, Repa JJ, Turley SD. Ontogenesis and Modulation of Intestinal Unesterified Cholesterol Sequestration in a Mouse Model of Niemann-Pick C1 Disease. Dig Dis Sci 2020; 65:158-167. [PMID: 31312996 DOI: 10.1007/s10620-019-05736-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/22/2019] [Accepted: 07/11/2019] [Indexed: 01/24/2023]
Abstract
BACKGROUND Mutations in the NPC1 gene result in sequestration of unesterified cholesterol (UC) and glycosphingolipids in most tissues leading to multi-organ disease, especially in the brain, liver, lungs, and spleen. Various data from NPC1-deficient mice suggest the small intestine (SI) is comparatively less affected, even in late stage disease. METHODS Using the Npc1nih mouse model, we measured SI weights and total cholesterol (TC) levels in Npc1-/- versus Npc1+/+ mice as a function of age, and then after prolonged ezetimibe-induced inhibition of cholesterol absorption. Next, we determined intestinal levels of UC and esterified cholesterol (EC), and cholesterol synthesis rates in Npc1-/- and Npc1+/+ mice, with and without the cholesterol-esterifying enzyme SOAT2, following a once-only subcutaneous injection with 2-hydroxypropyl-β-cyclodextrin (2HPβCD). RESULTS By ~ 42 days of age, intestinal TC levels averaged ~ 2.1-fold more (mostly UC) in the Npc1-/- versus Npc1+/+ mice with no further increase thereafter. Chronic ezetimibe treatment lowered intestinal TC levels in the Npc1-/- mice by only ~ 16%. In Npc1-/- mice given 2HPβCD 24 h earlier, UC levels fell, EC levels increased (although less so in mice lacking SOAT2), and cholesterol synthesis was suppressed equally in the Npc1-/-:Soat2+/+ and Npc1-/-:Soat2-/- mice. CONCLUSIONS The low and static levels of intestinal UC sequestration in Npc1-/- mice likely reflect the continual sloughing of cells from the mucosa. This sequestration is blunted by about the same extent following a single acute treatment with 2HPβCD as it is by a prolonged ezetimibe-induced block of cholesterol absorption.
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MESH Headings
- 2-Hydroxypropyl-beta-cyclodextrin/pharmacology
- Animals
- Cholesterol/metabolism
- Disease Models, Animal
- Ezetimibe/pharmacology
- Female
- Intestinal Absorption/drug effects
- Intestinal Mucosa/drug effects
- Intestinal Mucosa/metabolism
- Intestine, Small/drug effects
- Intestine, Small/metabolism
- Intracellular Signaling Peptides and Proteins/deficiency
- Intracellular Signaling Peptides and Proteins/genetics
- Male
- Mice, 129 Strain
- Mice, Inbred BALB C
- Mice, Inbred C57BL
- Mice, Knockout
- Niemann-Pick C1 Protein
- Niemann-Pick Disease, Type C/drug therapy
- Niemann-Pick Disease, Type C/genetics
- Niemann-Pick Disease, Type C/metabolism
- Sterol O-Acyltransferase/genetics
- Sterol O-Acyltransferase/metabolism
- Sterol O-Acyltransferase 2
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Affiliation(s)
- Adam M Lopez
- Department of Internal Medicine, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX, 75390, USA
| | - Charina M Ramirez
- Department of Pediatrics, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX, 75390, USA
| | - Anna M Taylor
- Department of Physiology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX, 75390, USA
- School of Behavioral and Brain Sciences, University of Texas at Dallas, Richardson, TX, 75080, USA
| | - Ryan D Jones
- Department of Physiology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX, 75390, USA
- Department of Pathology, Northwestern University, Chicago, IL, 60611, USA
| | - Joyce J Repa
- Department of Internal Medicine, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX, 75390, USA
- Department of Physiology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX, 75390, USA
| | - Stephen D Turley
- Department of Internal Medicine, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX, 75390, USA.
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11
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Haemmerle G, Lass A. Genetically modified mouse models to study hepatic neutral lipid mobilization. Biochim Biophys Acta Mol Basis Dis 2019; 1865:879-894. [PMID: 29883718 PMCID: PMC6887554 DOI: 10.1016/j.bbadis.2018.06.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2018] [Revised: 05/25/2018] [Accepted: 06/01/2018] [Indexed: 02/07/2023]
Abstract
Excessive accumulation of triacylglycerol is the common denominator of a wide range of clinical pathologies of liver diseases, termed non-alcoholic fatty liver disease. Such excessive triacylglycerol deposition in the liver is also referred to as hepatic steatosis. Although liver steatosis often resolves over time, it eventually progresses to steatohepatitis, liver fibrosis and cirrhosis, with associated complications, including liver failure, hepatocellular carcinoma and ultimately death of affected individuals. From the disease etiology it is obvious that a tight regulation between lipid uptake, triacylglycerol synthesis, hydrolysis, secretion and fatty acid oxidation is required to prevent triacylglycerol deposition in the liver. In addition to triacylglycerol, also a tight control of other neutral lipid ester classes, i.e. cholesteryl esters and retinyl esters, is crucial for the maintenance of a healthy liver. Excessive cholesteryl ester accumulation is a hallmark of cholesteryl ester storage disease or Wolman disease, which is associated with premature death. The loss of hepatic vitamin A stores (retinyl ester stores of hepatic stellate cells) is incidental to the onset of liver fibrosis. Importantly, this more advanced stage of liver disease usually does not resolve but progresses to life threatening stages, i.e. liver cirrhosis and cancer. Therefore, understanding the enzymes and pathways that mobilize hepatic neutral lipid esters is crucial for the development of strategies and therapies to ameliorate pathophysiological conditions associated with derangements of hepatic neutral lipid ester stores, including liver steatosis, steatohepatitis, and fibrosis. This review highlights the physiological roles of enzymes governing the mobilization of neutral lipid esters at different sites in liver cells, including cytosolic lipid droplets, endoplasmic reticulum, and lysosomes. This article is part of a Special Issue entitled Molecular Basis of Disease: Animal models in liver disease.
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Affiliation(s)
- Guenter Haemmerle
- Institute of Molecular Biosciences, University of Graz, Heinrichstraße 31/II, 8010 Graz, Austria.
| | - Achim Lass
- Institute of Molecular Biosciences, University of Graz, Heinrichstraße 31/II, 8010 Graz, Austria; BioTechMed-Graz, Austria.
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12
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Pajed L, Wagner C, Taschler U, Schreiber R, Kolleritsch S, Fawzy N, Pototschnig I, Schoiswohl G, Pusch LM, Wieser BI, Vesely P, Hoefler G, Eichmann TO, Zimmermann R, Lass A. Hepatocyte-specific deletion of lysosomal acid lipase leads to cholesteryl ester but not triglyceride or retinyl ester accumulation. J Biol Chem 2019; 294:9118-9133. [PMID: 31023823 PMCID: PMC6556574 DOI: 10.1074/jbc.ra118.007201] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Revised: 04/23/2019] [Indexed: 12/22/2022] Open
Abstract
Lysosomal acid lipase (LAL) hydrolyzes cholesteryl ester (CE) and retinyl ester (RE) and triglyceride (TG). Mice globally lacking LAL accumulate CE most prominently in the liver. The severity of the CE accumulation phenotype progresses with age and is accompanied by hepatomegaly and hepatic cholesterol crystal deposition. In contrast, hepatic TG accumulation is much less pronounced in these mice, and hepatic RE levels are even decreased. To dissect the functional role of LAL for neutral lipid ester mobilization in the liver, we generated mice specifically lacking LAL in hepatocytes (hep-LAL-ko). On a standard chow diet, hep-LAL-ko mice exhibited increased hepatic CE accumulation but unaltered TG and RE levels. Feeding the hep-LAL-ko mice a vitamin A excess/high-fat diet (VitA/HFD) further increased hepatic cholesterol levels, but hepatic TG and RE levels in these mice were lower than in control mice. Performing in vitro activity assays with lysosome-enriched fractions from livers of mice globally lacking LAL, we detected residual acid hydrolytic activities against TG and RE. Interestingly, this non-LAL acid TG hydrolytic activity was elevated in lysosome-enriched fractions from livers of hep-LAL-ko mice upon VitA/HFD feeding. In conclusion, the neutral lipid ester phenotype in livers from hep-LAL-ko mice indicates that LAL is limiting for CE turnover, but not for TG and RE turnovers. Furthermore, in vitro hydrolase activity assays revealed the existence of non-LAL acid hydrolytic activities for TG and RE. The corresponding acid lipase(s) catalyzing these reactions remains to be identified.
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Affiliation(s)
- Laura Pajed
- From the Institute of Molecular Biosciences, NAWI Graz, University of Graz, Heinrichstrasse 31/II
| | - Carina Wagner
- From the Institute of Molecular Biosciences, NAWI Graz, University of Graz, Heinrichstrasse 31/II
| | - Ulrike Taschler
- From the Institute of Molecular Biosciences, NAWI Graz, University of Graz, Heinrichstrasse 31/II
| | - Renate Schreiber
- From the Institute of Molecular Biosciences, NAWI Graz, University of Graz, Heinrichstrasse 31/II
| | - Stephanie Kolleritsch
- From the Institute of Molecular Biosciences, NAWI Graz, University of Graz, Heinrichstrasse 31/II
| | - Nermeen Fawzy
- From the Institute of Molecular Biosciences, NAWI Graz, University of Graz, Heinrichstrasse 31/II
| | - Isabella Pototschnig
- From the Institute of Molecular Biosciences, NAWI Graz, University of Graz, Heinrichstrasse 31/II
| | - Gabriele Schoiswohl
- From the Institute of Molecular Biosciences, NAWI Graz, University of Graz, Heinrichstrasse 31/II
| | - Lisa-Maria Pusch
- From the Institute of Molecular Biosciences, NAWI Graz, University of Graz, Heinrichstrasse 31/II
| | - Beatrix I Wieser
- the Diagnostic and Research Center for Molecular BioMedicine, Institute of Pathology, Medical University of Graz
| | - Paul Vesely
- the Diagnostic and Research Center for Molecular BioMedicine, Institute of Pathology, Medical University of Graz
| | - Gerald Hoefler
- the Diagnostic and Research Center for Molecular BioMedicine, Institute of Pathology, Medical University of Graz.,BioTechMed-Graz, 8010 Graz, Austria
| | - Thomas O Eichmann
- From the Institute of Molecular Biosciences, NAWI Graz, University of Graz, Heinrichstrasse 31/II.,the Center for Explorative Lipidomics, BioTechMed-Graz, and
| | - Robert Zimmermann
- From the Institute of Molecular Biosciences, NAWI Graz, University of Graz, Heinrichstrasse 31/II.,BioTechMed-Graz, 8010 Graz, Austria
| | - Achim Lass
- From the Institute of Molecular Biosciences, NAWI Graz, University of Graz, Heinrichstrasse 31/II, .,BioTechMed-Graz, 8010 Graz, Austria
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13
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Lopez AM, Jones RD, Repa JJ, Turley SD. Niemann-Pick C1-deficient mice lacking sterol O-acyltransferase 2 have less hepatic cholesterol entrapment and improved liver function. Am J Physiol Gastrointest Liver Physiol 2018; 315:G454-G463. [PMID: 29878847 PMCID: PMC6230690 DOI: 10.1152/ajpgi.00124.2018] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/11/2018] [Revised: 05/31/2018] [Accepted: 06/01/2018] [Indexed: 01/31/2023]
Abstract
Cholesteryl esters are generated at multiple sites in the body by sterol O-acyltransferase (SOAT) 1 or SOAT2 in various cell types and lecithin cholesterol acyltransferase in plasma. Esterified cholesterol and triacylglycerol contained in lipoproteins cleared from the circulation via receptor-mediated or bulk-phase endocytosis are hydrolyzed by lysosomal acid lipase within the late endosomal/lysosomal (E/L) compartment. Then, through the successive actions of Niemann-Pick C (NPC) 2 and NPC 1, unesterified cholesterol (UC) is exported from the E/L compartment to the cytosol. Mutations in either NPC1 or NPC2 lead to continuing entrapment of UC in all organs, resulting in multisystem disease, which includes hepatic dysfunction and in some cases liver failure. These studies investigated primarily whether elimination of SOAT2 in NPC1-deficient mice impacted hepatic UC sequestration, inflammation, and transaminase activities. Measurements were made in 7-wk-old mice fed a low-cholesterol chow diet or one enriched with cholesterol starting 2 wk before study. In the chow-fed mice, NPC1:SOAT2 double knockouts, compared with their littermates lacking only NPC1, had 20% less liver mass, 28% lower hepatic UC concentrations, and plasma alanine aminotransferase and aspartate aminotransferase activities that were decreased by 48% and 36%, respectively. mRNA expression levels for several markers of inflammation were all significantly lower in the NPC1 mutants lacking SOAT2. The existence of a new class of potent and selective SOAT2 inhibitors provides an opportunity for exploring if suppression of this enzyme could potentially become an adjunctive therapy for liver disease in NPC1 deficiency. NEW & NOTEWORTHY In Niemann-Pick type C1 (NPC1) disease, the entrapment of unesterified cholesterol (UC) in the endosomal/lysosomal compartment of all cells causes multiorgan disease, including neurodegeneration, pulmonary dysfunction, and liver failure. Some of this sequestered UC entered cells initially in the esterified form. When sterol O-acyltransferase 2, a cholesterol esterifying enzyme present in enterocytes and hepatocytes, is eliminated in NPC1-deficient mice, there is a reduction in their hepatomegaly, hepatic UC content, and cellular injury.
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Affiliation(s)
- Adam M Lopez
- Department of Internal Medicine, University of Texas Southwestern Medical Center , Dallas, Texas
| | - Ryan D Jones
- Department of Physiology, University of Texas Southwestern Medical Center , Dallas, Texas
| | - Joyce J Repa
- Department of Internal Medicine, University of Texas Southwestern Medical Center , Dallas, Texas
- Department of Physiology, University of Texas Southwestern Medical Center , Dallas, Texas
| | - Stephen D Turley
- Department of Internal Medicine, University of Texas Southwestern Medical Center , Dallas, Texas
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14
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Bowden KL, Dubland JA, Chan T, Xu YH, Grabowski GA, Du H, Francis GA. LAL (Lysosomal Acid Lipase) Promotes Reverse Cholesterol Transport In Vitro and In Vivo. Arterioscler Thromb Vasc Biol 2018; 38:1191-1201. [PMID: 29599133 DOI: 10.1161/atvbaha.117.310507] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2015] [Accepted: 03/13/2018] [Indexed: 11/16/2022]
Abstract
OBJECTIVE To explore the role of LAL (lysosomal acid lipase) in macrophage cholesterol efflux and whole-body reverse cholesterol transport. APPROACH AND RESULTS Immortalized peritoneal macrophages from lal-/- mice showed reduced expression of ABCA1 (ATP-binding cassette transporter A1) and ABCG1 (ATP-binding cassette transporter G1), reduced production of the regulatory oxysterol 27-hydroxycholesterol, and impaired suppression of cholesterol synthesis on exposure to acetylated low-density lipoprotein when compared with lal+/+ macrophages. LAL-deficient mice also showed reduced hepatic ABCG5 (ATP-binding cassette transporter G5) and ABCG8 (ATP-binding cassette transporter G8) expression compared with lal+/+ mice. LAL-deficient macrophages loaded with [3H]-cholesteryl oleate-labeled acetylated low-density lipoprotein showed impaired efflux of released [3H]-cholesterol to apoA-I (apolipoprotein A-I), with normalization of [3H]-cholesteryl ester levels and partial correction of ABCA1 expression and cholesterol efflux to apoA-I when treated with exogenous rhLAL (recombinant human LAL protein). LAL-deficient mice injected intraperitoneally with lal-/- macrophages cholesterol loaded and labeled in the same way exhibited only 1.55±0.35% total injected [3H]-cholesterol counts appearing in the feces for 48 h (n=30), compared with 5.38±0.92% in lal+/+ mice injected with labeled lal+/+ macrophages (n=27), P<0.001. To mimic the therapeutic condition of delivery of supplemental LAL in vivo, injection of labeled lal-/- macrophages into lal+/+ mice resulted in a significant increase in reverse cholesterol transport (2.60±0.46% of 3H-cholesterol counts in feces at 48 hours [n=19]; P<0.001 when compared with injection into lal-/- mice). CONCLUSIONS These results indicate a critical role for LAL in promoting both macrophage and whole-body reverse cholesterol transport and the ability of supplemental LAL to be taken up and correct reverse cholesterol transport in vivo.
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Affiliation(s)
- Kristin L Bowden
- From the Department of Medicine, Centre for Heart Lung Innovation, Institute for Heart + Lung Health, Providence Health Care Research Institute at St. Paul's Hospital, University of British Columbia, Vancouver, Canada (K.L.B., J.A.D., T.C., G.A.F.)
| | - Joshua A Dubland
- From the Department of Medicine, Centre for Heart Lung Innovation, Institute for Heart + Lung Health, Providence Health Care Research Institute at St. Paul's Hospital, University of British Columbia, Vancouver, Canada (K.L.B., J.A.D., T.C., G.A.F.)
| | - Teddy Chan
- From the Department of Medicine, Centre for Heart Lung Innovation, Institute for Heart + Lung Health, Providence Health Care Research Institute at St. Paul's Hospital, University of British Columbia, Vancouver, Canada (K.L.B., J.A.D., T.C., G.A.F.)
| | - You-Hai Xu
- Division of Human Genetics, Cincinnati Children's Hospital Medical Center, OH (Y.-H.X., G.A.G.).,Division of Human Genetics, Cincinnati Children's Hospital Medical Center, OH (Y.-H.X., G.A.G.)
| | - Gregory A Grabowski
- From the Department of Medicine, Centre for Heart Lung Innovation, Institute for Heart + Lung Health, Providence Health Care Research Institute at St. Paul's Hospital, University of British Columbia, Vancouver, Canada (K.L.B., J.A.D., T.C., G.A.F.).,Division of Human Genetics, Cincinnati Children's Hospital Medical Center, OH (Y.-H.X., G.A.G.).,Department of Pediatrics, University of Cincinnati College of Medicine, OH (Y.-H.X., G.A.G.)
| | - Hong Du
- Department of Pathology and Laboratory Medicine, Indiana University, Indianapolis (H.D.)
| | - Gordon A Francis
- From the Department of Medicine, Centre for Heart Lung Innovation, Institute for Heart + Lung Health, Providence Health Care Research Institute at St. Paul's Hospital, University of British Columbia, Vancouver, Canada (K.L.B., J.A.D., T.C., G.A.F.)
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15
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Lopez AM, Chuang JC, Turley SD. Impact of loss of SOAT2 function on disease progression in the lysosomal acid lipase-deficient mouse. Steroids 2018; 130:7-14. [PMID: 29246491 PMCID: PMC5760480 DOI: 10.1016/j.steroids.2017.11.015] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/08/2017] [Revised: 11/28/2017] [Accepted: 11/30/2017] [Indexed: 01/27/2023]
Abstract
Although only a small proportion of cholesterol in the body is esterified, in several diseases marked expansion of the esterified cholesterol (EC) pool occurs. These include Wolman disease (WD) and Cholesteryl Ester Storage Disease (CESD) which both result from mutations in LIPA, the gene that encodes lysosomal acid lipase (LAL). The respective contributions that our three cholesterol esterifying enzymes make to EC production, especially in disorders like CESD, are not well defined. The current studies represent a detailed exploration of our earlier findings in young male LAL-deficient mice also missing sterol O-acyltransferase 2 (SOAT2, also called ACAT2). Here we show that, even as they aged, male and female Lal-/-: Soat2- /- mice, compared to Lal-/-: Soat2+/+ littermates, had appreciably less hepatomegaly as well as a marked reduction in the level of sequestration of EC, in liver transaminase activities, and in hepatic mRNA expression levels for markers of inflammation. Loss of SOAT2 function also dramatically curtailed EC entrapment in the small intestine of the LAL-deficient mice. Together, these data imply that SOAT2 inhibition, if applied concurrently with enzyme replacement therapy for LAL deficiency, may blunt the re-esterification of newly released unesterified cholesterol thereby improving clinical outcomes.
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Affiliation(s)
- Adam M Lopez
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390, United States.
| | - Jen-Chieh Chuang
- Children's Research Institute, University of Texas Southwestern Medical Center, Dallas, TX 75390, United States.
| | - Stephen D Turley
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390, United States.
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16
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Chuang JC, Lopez AM, Turley SD. Quantitation of the rates of hepatic and intestinal cholesterol synthesis in lysosomal acid lipase-deficient mice before and during treatment with ezetimibe. Biochem Pharmacol 2017; 135:116-125. [PMID: 28322747 PMCID: PMC5489310 DOI: 10.1016/j.bcp.2017.03.010] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2017] [Accepted: 03/14/2017] [Indexed: 01/28/2023]
Abstract
Esterified cholesterol (EC) and triglycerides, contained within lipoproteins taken up by cells, are hydrolysed by lysosomal acid lipase (LAL) in the late endosomal/lysosomal (E/L) compartment. The resulting unesterified cholesterol (UC) is transported via Niemann-Pick type C2 and C1 into the cytosolic compartment where it enters a putative pool of metabolically active cholesterol that is utilized in accordance with cellular needs. Loss-of-function mutations in LIPA, the gene encoding LAL, result in dramatic increases in tissue concentrations of EC, a hallmark feature of Wolman disease and cholesteryl ester storage disease (CESD). The lysosomal sequestration of EC causes cells to respond to a perceived deficit of sterol by increasing their rate of cholesterol synthesis, particularly in the liver. A similar compensatory response occurs with treatments that disrupt the enterohepatic movement of cholesterol or bile acids. Here we measured rates of cholesterol synthesis in vivo in the liver and small intestine of a mouse model for CESD given the cholesterol absorption inhibitor ezetimibe from weaning until early adulthood. Consistent with previous findings, this treatment significantly reduced the amount of EC sequestered in the liver (from 132.43±7.35 to 70.07±6.04mg/organ) and small intestine (from 2.78±0.21 to 1.34±0.09mg/organ) in the LAL-deficient mice even though their rates of hepatic and intestinal cholesterol synthesis were either comparable to, or exceeded those in matching untreated Lal-/- mice. These data reveal the role of intestinal cholesterol absorption in driving the expansion of tissue EC content and disease progression in LAL deficiency.
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Affiliation(s)
- Jen-Chieh Chuang
- Department of Internal Medicine, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX, United States.
| | - Adam M Lopez
- Department of Internal Medicine, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX, United States.
| | - Stephen D Turley
- Department of Internal Medicine, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX, United States.
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17
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Schulze RJ, Sathyanarayan A, Mashek DG. Breaking fat: The regulation and mechanisms of lipophagy. Biochim Biophys Acta Mol Cell Biol Lipids 2017. [PMID: 28642194 DOI: 10.1016/j.bbalip.2017.06.008] [Citation(s) in RCA: 151] [Impact Index Per Article: 21.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Lipophagy is defined as the autophagic degradation of intracellular lipid droplets (LDs). While the field of lipophagy research is relatively young, an expansion of research in this area over the past several years has greatly advanced our understanding of lipophagy. Since its original characterization in fasted liver, the contribution of lipophagy is now recognized in various organisms, cell types, metabolic states and disease models. Moreover, recent studies provide exciting new insights into the underlying mechanisms of lipophagy induction as well as the consequences of lipophagy on cell metabolism and signaling. This review summarizes recent work focusing on LDs and lipophagy as well as highlighting challenges and future directions of research as our understanding of lipophagy continues to grow and evolve. This article is part of a Special Issue entitled: Recent Advances in Lipid Droplet Biology edited by Rosalind Coleman and Matthijs Hesselink.
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Affiliation(s)
- Ryan J Schulze
- Department of Biochemistry and Molecular Biology and the Center for Digestive Diseases, Mayo Clinic, Rochester, MN, United States
| | - Aishwarya Sathyanarayan
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN, United States
| | - Douglas G Mashek
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN, United States; Department of Medicine, Division of Diabetes, Endocrinology and Metabolism, University of Minnesota, Minneapolis, MN, United States.
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18
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Lopez AM, Chuang JC, Turley SD. Measurement of Rates of Cholesterol and Fatty Acid Synthesis In Vivo Using Tritiated Water. Methods Mol Biol 2017; 1583:241-256. [PMID: 28205179 DOI: 10.1007/978-1-4939-6875-6_18] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Every organ in the body is capable of synthesizing cholesterol de novo but at rates that vary with a constellation of factors. A significant proportion of the hydrogen atoms present in cholesterol that is synthesized in the body are derived from water. Thus, although water ordinarily makes up the bulk of body mass, the acute enrichment of the body water pool with a sufficiently large amount of tritiated water over a short interval of time (usually 1 h) yields measurable rates of incorporation of the labeled water into newly generated cholesterol and also fatty acids. Such data can provide a quantitative measure of how specific genetic, dietary, and pharmacological manipulations impact not just the rate of cholesterol synthesis in particular organs but also rates of whole-body cholesterol production and turnover.
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Affiliation(s)
- Adam M Lopez
- Division of Digestive and Liver Diseases, Department of Internal Medicine, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX, 75390-9151, USA
| | - Jen-Chieh Chuang
- Division of Digestive and Liver Diseases, Department of Internal Medicine, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX, 75390-9151, USA
| | - Stephen D Turley
- Division of Digestive and Liver Diseases, Department of Internal Medicine, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX, 75390-9151, USA.
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19
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Radović B, Vujić N, Leopold C, Schlager S, Goeritzer M, Patankar JV, Korbelius M, Kolb D, Reindl J, Wegscheider M, Tomin T, Birner-Gruenberger R, Schittmayer M, Groschner L, Magnes C, Diwoky C, Frank S, Steyrer E, Du H, Graier WF, Madl T, Kratky D. Lysosomal acid lipase regulates VLDL synthesis and insulin sensitivity in mice. Diabetologia 2016; 59:1743-52. [PMID: 27153842 PMCID: PMC4930475 DOI: 10.1007/s00125-016-3968-6] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/16/2015] [Accepted: 03/29/2016] [Indexed: 01/08/2023]
Abstract
AIMS/HYPOTHESIS Lysosomal acid lipase (LAL) hydrolyses cholesteryl esters and triacylglycerols (TG) within lysosomes to mobilise NEFA and cholesterol. Since LAL-deficient (Lal (-/-) ) mice suffer from progressive loss of adipose tissue and severe accumulation of lipids in hepatic lysosomes, we hypothesised that LAL deficiency triggers alternative energy pathway(s). METHODS We studied metabolic adaptations in Lal (-/-) mice. RESULTS Despite loss of adipose tissue, Lal (-/-) mice show enhanced glucose clearance during insulin and glucose tolerance tests and have increased uptake of [(3)H]2-deoxy-D-glucose into skeletal muscle compared with wild-type mice. In agreement, fasted Lal (-/-) mice exhibit reduced glucose and glycogen levels in skeletal muscle. We observed 84% decreased plasma leptin levels and significantly reduced hepatic ATP, glucose, glycogen and glutamine concentrations in fed Lal (-/-) mice. Markedly reduced hepatic acyl-CoA concentrations decrease the expression of peroxisome proliferator-activated receptor α (PPARα) target genes. However, treatment of Lal (-/-) mice with the PPARα agonist fenofibrate further decreased plasma TG (and hepatic glucose and glycogen) concentrations in Lal (-/-) mice. Depletion of hepatic nuclear factor 4α and forkhead box protein a2 in fasted Lal (-/-) mice might be responsible for reduced expression of microsomal TG transfer protein, defective VLDL synthesis and drastically reduced plasma TG levels. CONCLUSIONS/INTERPRETATION Our findings indicate that neither activation nor inactivation of PPARα per se but rather the availability of hepatic acyl-CoA concentrations regulates VLDL synthesis and subsequent metabolic adaptations in Lal (-/-) mice. We conclude that decreased plasma VLDL production enhances glucose uptake into skeletal muscle to compensate for the lack of energy supply.
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Affiliation(s)
- Branislav Radović
- Institute of Molecular Biology and Biochemistry, Center of Molecular Medicine, Medical University of Graz, Harrachgasse 21, 8010, Graz, Austria
| | - Nemanja Vujić
- Institute of Molecular Biology and Biochemistry, Center of Molecular Medicine, Medical University of Graz, Harrachgasse 21, 8010, Graz, Austria
| | - Christina Leopold
- Institute of Molecular Biology and Biochemistry, Center of Molecular Medicine, Medical University of Graz, Harrachgasse 21, 8010, Graz, Austria
| | - Stefanie Schlager
- Institute of Molecular Biology and Biochemistry, Center of Molecular Medicine, Medical University of Graz, Harrachgasse 21, 8010, Graz, Austria
| | - Madeleine Goeritzer
- Institute of Molecular Biology and Biochemistry, Center of Molecular Medicine, Medical University of Graz, Harrachgasse 21, 8010, Graz, Austria
| | - Jay V Patankar
- Institute of Molecular Biology and Biochemistry, Center of Molecular Medicine, Medical University of Graz, Harrachgasse 21, 8010, Graz, Austria
- Center for Molecular Medicine and Therapeutics, Department of Medical Genetics, University of British Columbia, Vancouver, BC, Canada
| | - Melanie Korbelius
- Institute of Molecular Biology and Biochemistry, Center of Molecular Medicine, Medical University of Graz, Harrachgasse 21, 8010, Graz, Austria
| | - Dagmar Kolb
- Center for Medical Research/Institute of Cell Biology, Histology and Embryology, Medical University of Graz, Graz, Austria
| | - Julia Reindl
- Institute of Molecular Biology and Biochemistry, Center of Molecular Medicine, Medical University of Graz, Harrachgasse 21, 8010, Graz, Austria
| | - Martin Wegscheider
- Institute of Molecular Biology and Biochemistry, Center of Molecular Medicine, Medical University of Graz, Harrachgasse 21, 8010, Graz, Austria
| | - Tamara Tomin
- Institute of Pathology, Medical University of Graz, Graz, Austria
- Omics Center Graz, BioTechMed-Graz, Graz, Austria
| | - Ruth Birner-Gruenberger
- Institute of Pathology, Medical University of Graz, Graz, Austria
- Omics Center Graz, BioTechMed-Graz, Graz, Austria
| | - Matthias Schittmayer
- Institute of Pathology, Medical University of Graz, Graz, Austria
- Omics Center Graz, BioTechMed-Graz, Graz, Austria
| | - Lukas Groschner
- Institute of Molecular Biology and Biochemistry, Center of Molecular Medicine, Medical University of Graz, Harrachgasse 21, 8010, Graz, Austria
- Center for Neural Circuits and Behaviour, University of Oxford, Oxford, UK
| | - Christoph Magnes
- Health, Bioanalytik und Metabolomics, Joanneum Research, Graz, Austria
| | - Clemens Diwoky
- Institute of Biomedical Engineering, Graz University of Technology, Graz, Austria
- Institute of Molecular Biosciences, University of Graz, Graz, Austria
| | - Saša Frank
- Institute of Molecular Biology and Biochemistry, Center of Molecular Medicine, Medical University of Graz, Harrachgasse 21, 8010, Graz, Austria
| | - Ernst Steyrer
- Institute of Molecular Biology and Biochemistry, Center of Molecular Medicine, Medical University of Graz, Harrachgasse 21, 8010, Graz, Austria
| | - Hong Du
- Department of Pathology and Laboratory Medicine, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Wolfgang F Graier
- Institute of Molecular Biology and Biochemistry, Center of Molecular Medicine, Medical University of Graz, Harrachgasse 21, 8010, Graz, Austria
| | - Tobias Madl
- Institute of Molecular Biology and Biochemistry, Center of Molecular Medicine, Medical University of Graz, Harrachgasse 21, 8010, Graz, Austria
- Omics Center Graz, BioTechMed-Graz, Graz, Austria
- Department of Chemistry, Technical University, Munich, Germany
- Institute of Structural Biology, Helmholtz Zentrum, Munich, Germany
| | - Dagmar Kratky
- Institute of Molecular Biology and Biochemistry, Center of Molecular Medicine, Medical University of Graz, Harrachgasse 21, 8010, Graz, Austria.
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Grumet L, Eichmann TO, Taschler U, Zierler KA, Leopold C, Moustafa T, Radovic B, Romauch M, Yan C, Du H, Haemmerle G, Zechner R, Fickert P, Kratky D, Zimmermann R, Lass A. Lysosomal Acid Lipase Hydrolyzes Retinyl Ester and Affects Retinoid Turnover. J Biol Chem 2016; 291:17977-87. [PMID: 27354281 PMCID: PMC5016185 DOI: 10.1074/jbc.m116.724054] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Indexed: 11/17/2022] Open
Abstract
Lysosomal acid lipase (LAL) is essential for the clearance of endocytosed cholesteryl ester and triglyceride-rich chylomicron remnants. Humans and mice with defective or absent LAL activity accumulate large amounts of cholesteryl esters and triglycerides in multiple tissues. Although chylomicrons also contain retinyl esters (REs), a role of LAL in the clearance of endocytosed REs has not been reported. In this study, we found that murine LAL exhibits RE hydrolase activity. Pharmacological inhibition of LAL in the human hepatocyte cell line HepG2, incubated with chylomicrons, led to increased accumulation of REs in endosomal/lysosomal fractions. Furthermore, pharmacological inhibition or genetic ablation of LAL in murine liver largely reduced in vitro acid RE hydrolase activity. Interestingly, LAL-deficient mice exhibited increased RE content in the duodenum and jejunum but decreased RE content in the liver. Furthermore, LAL-deficient mice challenged with RE gavage exhibited largely reduced post-prandial circulating RE content, indicating that LAL is required for efficient nutritional vitamin A availability. In summary, our results indicate that LAL is the major acid RE hydrolase and required for functional retinoid homeostasis.
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Affiliation(s)
- Lukas Grumet
- From the Institute of Molecular Biosciences, University of Graz, 8010 Graz, Austria
| | - Thomas O Eichmann
- From the Institute of Molecular Biosciences, University of Graz, 8010 Graz, Austria
| | - Ulrike Taschler
- From the Institute of Molecular Biosciences, University of Graz, 8010 Graz, Austria
| | - Kathrin A Zierler
- From the Institute of Molecular Biosciences, University of Graz, 8010 Graz, Austria
| | | | - Tarek Moustafa
- Laboratory of Experimental and Molecular Hepatology, Division of Gastroenterology and Hepatology, Department of Internal Medicine, Medical University of Graz, 8010 Graz, Austria
| | | | - Matthias Romauch
- From the Institute of Molecular Biosciences, University of Graz, 8010 Graz, Austria
| | - Cong Yan
- the Department of Pathology and Laboratory Medicine and Indiana University Simon Cancer Center, Indiana University School of Medicine, Indianapolis, Indiana 46202, and
| | - Hong Du
- the Department of Pathology and Laboratory Medicine and Indiana University Simon Cancer Center, Indiana University School of Medicine, Indianapolis, Indiana 46202, and
| | - Guenter Haemmerle
- From the Institute of Molecular Biosciences, University of Graz, 8010 Graz, Austria
| | - Rudolf Zechner
- From the Institute of Molecular Biosciences, University of Graz, 8010 Graz, Austria
| | - Peter Fickert
- Laboratory of Experimental and Molecular Hepatology, Division of Gastroenterology and Hepatology, Department of Internal Medicine, Medical University of Graz, 8010 Graz, Austria
| | - Dagmar Kratky
- the Institute of Molecular Biology and Biochemistry and
| | - Robert Zimmermann
- From the Institute of Molecular Biosciences, University of Graz, 8010 Graz, Austria
| | - Achim Lass
- From the Institute of Molecular Biosciences, University of Graz, 8010 Graz, Austria, BioTechMed, Graz 8010, Austria
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Yamada S, Guo X, Wang K, Tanimoto A, Sasaguri Y. Novel function of histamine signaling via histamine receptors in cholesterol and bile acid metabolism: Histamine H2 receptor protects against nonalcoholic fatty liver disease. Pathol Int 2016; 66:376-85. [PMID: 27321390 DOI: 10.1111/pin.12423] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2016] [Revised: 04/11/2016] [Accepted: 05/18/2016] [Indexed: 01/01/2023]
Affiliation(s)
- Sohsuke Yamada
- Department of Pathology, Field of Oncology, Kagoshima University Graduate School of Medical and Dental Sciences Kagoshima Japan
- Department of Pathology and Cell Biology School of Medicine, University of Occupational and Environmental Health Kitakyushu Japan
| | - Xin Guo
- Department of Pathology, Field of Oncology, Kagoshima University Graduate School of Medical and Dental Sciences Kagoshima Japan
- Department of Pathology and Cell Biology School of Medicine, University of Occupational and Environmental Health Kitakyushu Japan
- Laboratory of Pathology, Hebei Cancer Institute, the Fourth Hospital of Hebei Medical University Shijiazhuang China
| | - Ke‐Yong Wang
- Department of Pathology and Cell Biology School of Medicine, University of Occupational and Environmental Health Kitakyushu Japan
- Shared‐Use Research Center School of Medicine, University of Occupational and Environmental Health Kitakyushu Japan
| | - Akihide Tanimoto
- Department of Pathology, Field of Oncology, Kagoshima University Graduate School of Medical and Dental Sciences Kagoshima Japan
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22
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Lopez AM, Chuang JC, Posey KS, Ohshiro T, Tomoda H, Rudel LL, Turley SD. PRD125, a potent and selective inhibitor of sterol O-acyltransferase 2 markedly reduces hepatic cholesteryl ester accumulation and improves liver function in lysosomal acid lipase-deficient mice. J Pharmacol Exp Ther 2015; 355:159-67. [PMID: 26283692 PMCID: PMC4613965 DOI: 10.1124/jpet.115.227207] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2015] [Accepted: 08/14/2015] [Indexed: 11/22/2022] Open
Abstract
In most organs, the bulk of cholesterol is unesterified, although nearly all possess a varying capability of esterifying cholesterol through the action of either sterol O-acyltransferase (SOAT) 1 or, in the case of hepatocytes and enterocytes, SOAT2. Esterified cholesterol (EC) carried in plasma lipoproteins is hydrolyzed by lysosomal acid lipase (LAL) when they are cleared from the circulation. Loss-of-function mutations in LIPA, the gene that encodes LAL, result in Wolman disease or cholesteryl ester storage disease (CESD). Hepatomegaly and a massive increase in tissue EC levels are hallmark features of both disorders. While these conditions can be corrected with enzyme replacement therapy, the question arose as to whether pharmacological inhibition of SOAT2 might reduce tissue EC accretion in CESD. When weaned at 21 days, Lal(-/-) mice, of either gender, had a whole liver cholesterol content that was 12- to 13-fold more than that of matching Lal(+/+) littermates (23 versus 1.8 mg, respectively). In Lal(-/-) males given the selective SOAT2 inhibitor PRD125 1,11-O-o-methylbenzylidene-7-O-p-cyanobenzoyl-1,7,11-trideacetylpyripyropene A in their diet (∼10 mg/day per kg body weight) from 21 to 53 days, whole liver cholesterol content was 48.6 versus 153.7 mg in untreated 53-day-old Lal(-/-) mice. This difference reflected a 59% reduction in hepatic EC concentration (mg/g), combined with a 28% fall in liver mass. The treated mice also showed a 63% reduction in plasma alanine aminotransferase activity, in parallel with decisive falls in hepatic mRNA expression levels for multiple proteins that reflect macrophage presence and inflammation. These data implicate SOAT2 as a potential target in CESD management.
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Affiliation(s)
- Adam M Lopez
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas (A.M.L., J-C.C., K.S.P., S.D.T.); Graduate School of Pharmaceutical Science, Kitasato University, Tokyo, Japan (T.O., H.T.); and Department of Pathology, Wake Forest University School of Medicine, Winston-Salem, North Carolina (T.O., L.L.R.)
| | - Jen-Chieh Chuang
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas (A.M.L., J-C.C., K.S.P., S.D.T.); Graduate School of Pharmaceutical Science, Kitasato University, Tokyo, Japan (T.O., H.T.); and Department of Pathology, Wake Forest University School of Medicine, Winston-Salem, North Carolina (T.O., L.L.R.)
| | - Kenneth S Posey
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas (A.M.L., J-C.C., K.S.P., S.D.T.); Graduate School of Pharmaceutical Science, Kitasato University, Tokyo, Japan (T.O., H.T.); and Department of Pathology, Wake Forest University School of Medicine, Winston-Salem, North Carolina (T.O., L.L.R.)
| | - Taichi Ohshiro
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas (A.M.L., J-C.C., K.S.P., S.D.T.); Graduate School of Pharmaceutical Science, Kitasato University, Tokyo, Japan (T.O., H.T.); and Department of Pathology, Wake Forest University School of Medicine, Winston-Salem, North Carolina (T.O., L.L.R.)
| | - Hiroshi Tomoda
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas (A.M.L., J-C.C., K.S.P., S.D.T.); Graduate School of Pharmaceutical Science, Kitasato University, Tokyo, Japan (T.O., H.T.); and Department of Pathology, Wake Forest University School of Medicine, Winston-Salem, North Carolina (T.O., L.L.R.)
| | - Lawrence L Rudel
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas (A.M.L., J-C.C., K.S.P., S.D.T.); Graduate School of Pharmaceutical Science, Kitasato University, Tokyo, Japan (T.O., H.T.); and Department of Pathology, Wake Forest University School of Medicine, Winston-Salem, North Carolina (T.O., L.L.R.)
| | - Stephen D Turley
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas (A.M.L., J-C.C., K.S.P., S.D.T.); Graduate School of Pharmaceutical Science, Kitasato University, Tokyo, Japan (T.O., H.T.); and Department of Pathology, Wake Forest University School of Medicine, Winston-Salem, North Carolina (T.O., L.L.R.)
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23
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Lopez AM, Posey KS, Turley SD. Deletion of sterol O-acyltransferase 2 (SOAT2) function in mice deficient in lysosomal acid lipase (LAL) dramatically reduces esterified cholesterol sequestration in the small intestine and liver. Biochem Biophys Res Commun 2014; 454:162-6. [PMID: 25450374 PMCID: PMC4312202 DOI: 10.1016/j.bbrc.2014.10.063] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2014] [Accepted: 10/13/2014] [Indexed: 11/21/2022]
Abstract
Sterol O-acyltransferase 2 (SOAT2), also known as ACAT2, is the major cholesterol esterifying enzyme in the liver and small intestine (SI). Esterified cholesterol (EC) carried in certain classes of plasma lipoproteins is hydrolyzed by lysosomal acid lipase (LAL) when they are cleared from the circulation. Loss-of-function mutations in LIPA, the gene that encodes LAL, result in Wolman disease (WD) or cholesteryl ester storage disease (CESD). Hepatomegaly and a massive increase in tissue EC levels are hallmark features of both disorders. While these conditions can be corrected with enzyme replacement therapy, the question arose as to what effect the loss of SOAT2 function might have on tissue EC sequestration in LAL-deficient mice. When weaned at 21 days, Lal(-)(/)(-):Soat2(+)(/)(+) mice had a whole liver cholesterol content (mg/organ) of 24.7 mg vs 1.9mg in Lal(+/+):Soat2(+/+) littermates, with almost all the excess sterol being esterified. Over the next 31 days, liver cholesterol content in the Lal(-)(/)(-):Soat2(+)(/)(+) mice increased to 145 ± 2 mg but to only 29 ± 2 mg in their Lal(-)(/)(-):Soat2(-)(/)(-) littermates. The level of EC accumulation in the SI of the Lal(-)(/)(-):Soat2(-)(/)(-) mice was also much less than in their Lal(-)(/)(-):Soat2(+)(/)(+) littermates. In addition, there was a >70% reduction in plasma transaminase activities in the Lal(-)(/)(-):Soat2(-)(/)(-) mice. These studies illustrate how the severity of disease in a mouse model for CESD can be substantially ameliorated by elimination of SOAT2 function.
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Affiliation(s)
- Adam M Lopez
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390-9151, United States.
| | - Kenneth S Posey
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390-9151, United States.
| | - Stephen D Turley
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390-9151, United States.
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